As a faculty member of the Johns Hopkins Endocrinology Division with a background in laboratory research and a commitment to public health, my scientific and clinical focus is on using innovative translational approaches to understand the molecular mechanisms and role of environmental factors in the development of organ specific autoimmunity, using thyroid disease a model system. Autoimmune thyroid disease affects millions of people and is thought to be the leading autoimmune disease. In the NHANESIII survey, 4.7% of the US population self-reported thyroid disease, 5.9% had abnormal thyroid function tests, and 15.6% of euthyroid white women have thyroid antibodies indicating possible susceptibility. The NHANESIII study also found that one third of those being treated for thyroid disease were not euthyroid. This means that errors in therapy leave millions of people at risk for the long-term consequences of thyroid dysfunction, which can include heart failure, atrial fibrillation, and stroke. During the award period, I will build on my strong foundaion in research to acquire the additional expertise I need in immunology and clinical research techniques to develop a career focused on using thyroid disease as a powerful model to understand the mechanisms of organ-specific autoimmunity. The long term goals of this work are to improve diagnostic and prognostic tools, and support the development of strategies to abort disease progression before there is irreversible tissue destruction. This proposal will test our hypothesis that autoimmune disease requires both the activation/proliferation of self-reactive lymphocytes and an altered target tissue microenvironment that promotes ongoing inflammation. Our approach takes advantage of the unique disease model of pharmacologically triggered thyroid disease to examine the onset of disease prospectively in clinical populations exposed to immunomodulatory agents, with parallel mechanistic experiments with primary thyroid cells in vitro. Thyroid dysfunction is a frequent and potentially severe side effect of broad-spectrum immunomodulatory therapies such as interferon alpha (IFN?). Novel therapies that act specifically on T-cell regulatory pathways appear to have lower rates of thyroid disease. The first of these to be approved by the FDA, Ipilimumab, is now actively being used in the treatment of melanoma, a disease for which IFN? is also a standard therapy. In our analyses of thyroid disorders in 1233 initially euthyroid subjects treated for up to one year with IFN? for hepatitis C in the ACHIEVE study, interferon-induced thyroid disease (IITD) occurred in 16.7% of patients, with similar results found in the analysis of a second cohort. In contrast, phase 3 trials of Ipilimumab report thyroid dysfunction rates of 2-4%. Biphasic thyroiditis proved to be the most common, and most frequent clinically significant form of IITD in our published analyses. Although prior authors have proposed that biphasic thyroiditis is not an immune-mediated process, we found that it was strongly predicted by female sex, supporting the hypothesis that autoimmunity plays a dominant role in IITD. Therefore, Aim 1 will test the hypothesis that IITD-induced destructive thyroiditis is autoimmune in the IFN?-treated cohorts of ACHIEVE by asking which subtypes of IITD are predicted by the presence of pre-treatment anti-thyroid autoantibodies, markers for latent autoimmunity. Post-treatment antibody levels will be measured to investigate the extent to which latent disease is induced by exposure and to ask whether antibody-negative patients who develop IITD also develop evidence of autoimmunity. Aim 2 proceeds to test the proposed mechanism directly, first by confirming across individuals that pro-inflammatory changes, such as the increased major histocompatibility complex 1 expression seen in our preliminary data, occur in IFN?-exposed thyrocytes. We will then test whether the altered microenvironment is sufficient to enhance the activation of CD8+ cytotoxic T cells in vitro. Through a collaboration with international leaders in cancer immunotherapy in the Melanoma Group here at Johns Hopkins, Aim 3 will test the hypothesis in a clinical setting, by asking whether Ipilimumab is able to increase the incidence of latent anti-thyroid autoimmunity without triggering thyroid destruction in a prospectively analyzed cohort of melanoma patients undergoing therapy. I have phenomenal institutional resources available to gain expertise in immunology, statistics and clinical trials as well as grow my technical competence with important laboratory procedures including microarray and analysis of large data sets, flow cytometry techniques, and a variety of assays of lymphocyte function. I have an outstanding mentorship team to guide my development and assist me in all aspects of the research and my professional growth. My mentors, Dr. Paul Ladenson and Dr. Antony Rosen, both world leaders in their fields of thyroidology and autoimmunity respectively, provide me with tremendous intellectual and financial resources. The proposal includes developing in vitro assay systems, clinical cohorts and depth of knowledge that will support my successful transition to independent, RO1 funded, patient-oriented research.